An object is to provide an electron gun that can extend the lifetime of a photocathode. The object can be achieved by an electron gun including: a substrate having a photocathode film formed on a first face; a light source for irradiating the photocathode film with excitation light; an anode; a heater device for heating the photocathode film and/or the substrate; and an output adjustment device that adjusts a heating temperature of the heater device.

Provided in the present disclosure is an electron emitting element 10 including a laminated structure in which a first electrode 1, an electron accelerating layer 6 made of an insulation film, a second electrode 3, and a cover film 7 are laminated in that order, in which the second electrode is an electrode which transmits electrons and emits electrons from a surface thereof, and the cover film is a film which transmits electrons, is a protective film made of a material different from that of the second electrode, and constitutes an electron emission surface 5.

An electron gun comprising a cathode having an electron emitting surface and whose planar shape is circular, a heater to increase the temperature of the cathode, and an anode to apply a positive electric potential relative to the cathode to extract electrons in a predetermined direction is provided. The cathode comprises a through hole at a central portion thereof along a central axis of the cathode, and either the cathode comprises a no-emitting layer at at least one of an opening edge on the electron emitting surface side of the through hole and an inner surface of the through hole, or the opening edge on the electron emitting surface side of the through hole is a chamfered C surface or a chamfered R surface.

An electron gun comprising a cathode having an electron emitting surface and whose planar shape is circular, a heater to increase the temperature of the cathode, and an anode to apply a positive electric potential relative to the cathode to extract electrons in a predetermined direction is provided. The cathode comprises a through hole at a central portion thereof along a central axis of the cathode, and either the cathode comprises a no-emitting layer at at least one of an opening edge on the electron emitting surface side of the through hole and an inner surface of the through hole, or the opening edge on the electron emitting surface side of the through hole is a chamfered C surface or a chamfered R surface.

According to an embodiment of the present disclosure, a thermionic cathode includes: a cathode body having an outer surface, and a sealing layer including one or more graphene sheets on the outer surface of the cathode body. According to another embodiment of the present disclosure, a method for manufacturing a thermionic cathode includes: depositing a sealing layer including one or more graphene sheets on an outer surface of a cathode body.

A vented electrode that provides a directional stop to prevent energetic particles and secondaries (i.e., secondary electrons, charged particles, photons) generated in the vent channel from reaching into a gap outside of the electrode plate. For example, ventilation is added to at least one electrode, via vented inserts, wherein the vents do not provide a direct line of sight from at least one side of the electrode plate to the other.

A vented electrode that provides a directional stop to prevent energetic particles and secondaries (i.e., secondary electrons, charged particles, photons) generated in the vent channel from reaching into a gap outside of the electrode plate. For example, ventilation is added to at least one electrode, via vented inserts, wherein the vents do not provide a direct line of sight from at least one side of the electrode plate to the other.

A filament assembly 10 for an x-ray tube 20 can include a planar filament 11 electrically-coupled between and substantially-encircled by a pair of collector plates C1 and C2. The pair of collector plates C1 and C2 can support the planar filament 11 so that it does not twist or warp and align the filament assembly 10 within a cathode cup 33. The pair of collector plates C1 and C2 can block electrons emitted from a back side of the filament. Without the collector plates C1 and C2, back side electrons can change direction by about 180, hit the target, and distort a target electron spot. Each collector plate C1 or C2 can include holes H1 and H2. These holes H1 and H2 can aid in alignment of the collector plates C1 and C2 with electrodes 31 and electrode 32, can allow welding at a lower temperature, and can facilitate weld inspection.